Induction foil cap sealer

ABSTRACT

An induction foil cap sealer includes a sealing head module and power supply module that can be separately mounted and replaced. Both modules are convection air-cooled without a requirement for forced air-cooling or water cooling.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.60/259,202 filed Dec. 29, 2000.

FIELD OF THE INVENTION

The present invention relates generally to an induction foil cap sealer,and specifically to a modular induction foil cap sealer that isefficiently cooled without the use of either cooling water or forced aircooling.

BACKGROUND OF THE INVENTION

It is known in the art to secure metal foil seals to the cap of acontainer by passing the cap with the metal foil seal seated on itthrough a magnetic field generated by applying a high frequency currentto an inductor coil. The magnetic field inductively heats the metalfoil, which in turn heats and cures a sealing material adhering to thefoil. The sealing material, typically a thermoplastic resin, sets andseals to the lip of the container's opening. Known foil cap sealers havecomponents that require water cooling and/or forced air cooling. Forexample, the inductor could be a hollow copper tubing or bus bar that iscooled by running water through the hollow passage of the tubing or busbar. The use of Litz wire, which is known in the art, reduced heatlosses to the extent that forced conduction air cooling of the foil capsealer became feasible. Forced conduction air cooling, with therequirement for one or more typically electrically driven fans, requiresadditional energy consumption and increases the volume and weight of thefoil cap sealing equipment.

Additionally, foil cap sealers known in the art consist of a unitaryenclosure that includes the sealing head and a high frequency powersupply. The unitary enclosure must be supported and suspended over aprocessing line that transports the caps of the containers under thesealing head to heat the foil seals. This arrangement substantiallyincreases the weight that must be supported over the processing line.Additionally, failure in the power supply or failure in the sealing headwill necessitate the replacement of the entire foil cap sealer's unitaryenclosure.

Therefore, there exists the need for a modular air-cooled, energyefficient induction cap sealer that will not require forced air or watercooling.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the present invention is an induction foil cap sealerthat is used to secure a foil cap to the cap of a container. The foilsealer includes a sealing head module and a power supply module. A coilassembly is provided in the sealing head module. The coil assemblyincludes a magnetic flux concentrator, such as a ferrite core, and anair-cooled inductor disposed adjacent to the magnetic flux concentrator.In one embodiment of the invention, a frame surrounds the sides of thecore and a cover plate is attached to the top of the ferrite coil andinductor. At least one evaporator element of one or more heat pipes isin contact with the magnetic flux concentrator. A thermally conductivematerial, such as a coil plate, may be inserted between the magneticflux concentrator and the at least one evaporator element. Means areprovided for connecting the evaporator elements to at least onecondenser element of the one or more heat pipes so that the heat pipe'sheat media can transfer heat from the evaporator to the condenserelements. In one embodiment of the invention, the inductor is a Litzwire that is seated in a ferrite core. The ferrite core is formed fromU-shaped ferrite segments. A control panel may be included with thesealing heading module or may be remotely located.

In another aspect the present invention is a method of sealing a foilcap seated on the cap of a container to the cap. A sealing head assemblyis provided with an air-cooled inductor disposed adjacent to a magneticflux concentrator, such as a ferrite core. An ac current is provided tothe inductor from a power supply that is located remotely from thesealing head assembly. Current flow through the inductor creates amagnetic field that generates heat in the ferrite core. Generated heatis transferred to ambient air without the requirement for water coolingor forced air cooling. These and other aspects of the invention are setforth in the specification and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For the purpose of illustrating the invention, there is shown in thedrawings a form that is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIG. 1 is a front elevational view of one example of an induction foilcap sealer of the present invention.

FIG. 2 is a front elevational view of one example of a sealing headmodule used with an induction foil cap sealer of the present invention.

FIG. 3 is a cross-sectional view of a sealing head module withsectioning plane defined by line A—A in FIG. 2.

FIG. 4 is a side elevational view of a sealing head module.

FIG. 5 is a bottom view of a sealing head module.

FIG. 6 is an exploded perspective view of a coil assembly used with aninduction foil cap sealer of the present invention.

FIG. 7(a) is a top view of an assembled coil assembly.

FIG. 7(b) is a cross-sectional view of an assembled coil assembly withsectioning plane defined by line B—B in FIG. 7(a).

FIG. 8 is one example of a heat pipe used with an induction foil capsealer of the present invention.

DETAILED DESCRIPTION

Referring now to the drawings, wherein like numerals indicate likeelements there is shown in the figures one example of an induction foilcap sealer 10 of the present invention. The foil cap sealer comprises asealing head 20 and a power supply 60 suitably mounted on supportstructure 15. The power supply module is separate from the sealing headmodule, that is, the power supply module is located remotely from thesealing head module. One or more electrical conductors 17 are used toconnect the ac output of the power supply to an inductor in the sealinghead, and to provide control signals between the sealing head and thepower supply. Sealing head 20 is suitably mounted relative to conveyormeans 90 (shown in dashed lines in FIG. 1) so that containers 92 travelunder the bottom of the sealing head. The magnetic field generated bycurrent flowing through the inductor in the sealing head 20 is used toinductively heat a conductive foil that has been inserted within cap 94of a container. The foil in turn heats a temperature sensitive materialassociated with the foil so that the material melts and then adheres tothe lip of the container's opening to form a tamperproof seal. Althoughpower supply 60 is shown mounted on the same structural support as thatfor the sealing head, in alternative examples, the power supply may belocated in other remote locations. The operating ac output frequency ofthe power supply will depend upon the particular application of the foilcap sealer.

FIG. 2 through FIG. 8 show further details of the sealing head 20. Thesealing head includes a coil assembly 30, as further disclosed below,and elements of one or more heat pipes 40 that serve as a heat exchangerto remove heat generated primarily in the ferrite core by the inducedmagnetic field produced by ac current flow in the inductor, and in theinductor from the ac current flow. The ferrite core serves as a magneticflux concentrator. Typically, the sealing head will also include acontrol panel 22, which in this example is mounted in an enclosure onthe sealing head. The control panel incorporates suitable operatorinterfaces such as pushbuttons, keypads and visual display devices. Inalternative examples, the control panel may be remotely located.

As best illustrated in FIG. 6 and FIG. 7(b), inductor 31 is seated in aferrite core 32 for this example of the foil cap sealer of the presentinvention. In other examples of the invention the inductor is disposedadjacent to a magnetic flux concentrator, such as a ferrite core. In thepresent example, inductor 31 comprises a Litz wire with strand count andgauge suitably selected for the applied frequency range of power in aparticular application. Litz wire selections will generally be foroperating power frequencies between 50 and 200 kHz. Other types ofair-cooled inductors with suitable current densities and heatdissipation rates can also be used. Further in alternative examples ofthe invention, two or more air-cooled inductors can be arranged inferrite core 32 to suit a particular application. In the example shownin FIG. 6, the ferrite core comprises multiple U-shaped ferritesegments, which are assembled to provide a seating volume for inductor31. The ferrite segments consist of two types, namely long segments32(a) and short segments 32(b). Alternative configurations for theferrite segments can be used. A non-electrically conductive frame 34 isdisposed around the sides of the ferrite core. The frame includes alongitudinal, non-electrically conductive strip 34(a) that is disposedalong the longitudinal bottom surface of the exterior “U” legs of theferrite segments. A suitable but not exclusive material for the frameand strips is a NEMA Grade G-10 epoxy/glass composition. Cover plate 36closes the coil opening within frame 34, and can be formed from asuitable high temperature plastic or other non-electrically conductivematerial. The cover plate provides physical containment and protectionof the inductor and is not essential in all embodiments of the presentinvention. The frame, strips, and cover plate form an enclosure for theferrite core and inductor. The detailed form and configurations of thesecomponents will vary as the shape of the ferrite core and inductor vary.Other methods of enclosure or a ferrite core and inductor withoutenclosure can be employed with the foil cap sealer of the presentinvention. Coil plate 38 attaches to the base of the ferrite core. Thecoil plate is formed from a suitable thermally conductive material suchas aluminum. As illustrated in FIG. 7(b) a thermal epoxy 39 or othersuitable filler material can be used to fill the voids in an assembledcoil assembly to ensure proper seating of the inductor against theferrite core.

One side of plate 35 provides a suitable means for attachment of coilassembly 30 as shown in FIG. 3. The opposing side of the plate providesa suitable means for: mounting electrical components associated withinductor 31, such as a power transformer and a capacitor for tuning anLC circuit formed by the inductor and the capacitor; connectingcomponents that may be required for electrical conductors 17 from powersupply 60; and connecting means for the terminating ends of inductor 31to components mounted on the plate. In alternative arrangements, coilplate 38 may also serve as the mounting means for the above componentswithout the need for plate 35. Selection of an operating frequency isbased upon operating parameters (such as the speed of conveyor means 90)of foil cap sealer 10 and the configuration (such as the diameter of theopening of a container) of containers 92. The capacitor is selected foroptimum operating efficiency of the LC circuit at the selected operatingfrequency. If a change in operating frequency is desired, the capacitorcan be replaced with another capacitor having an appropriate capacitancefor optimum efficiency of the LC circuit without changing inductor 31.

The typical heat pipe configuration used with the modular induction foilcap sealer is shown in FIG. 8. Evaporator elements 42 of one or moreheat pipes 40 are placed in close contact with coil plate 38. Heatcreated primarily in the ferrite core 32 and air-cooled inductor 31 isconducted away from the core through the coil plate and to evaporatorelements 42 of the heat pipe. The ferrite core 32 and inductor 31 arethe primary sources of heat generation when an ac current is flowingthrough the inductor. As mentioned above coil plate 38 serves as athermally conductive material. In alternative examples of the invention,the evaporator elements 42 may be disposed directly adjacent to theferrite core or magnetic flux concentrator to remove heat from theferrite core and inductor. The heat transfer media, such as awater-based fluid or other suitable liquid, contained within the sealedevaporator elements 42 absorbs the heat. Each connecting tube 44 has oneend of its interior passage connected to the sealed interior of anevaporator element, and the opposing end connected to the sealedinterior of a condenser element 46. The connecting tube serves as aconnector that provides a path for the heat transfer media from anevaporator element to a condenser element. The heated media movesthrough the one or more connecting tubes 44 to the one or more condenserelements 46 in which the transfer media radiates heat to the surroundingambient medium, which is generally air within a normal room temperaturerange. The condenser elements are designed for a particular applicationto have a sufficient surface area that will result in an adequate heatdissipation rate at rated output of the power supply so that forced air(fan) cooling or water (or other fluid) cooling of the ferrite core andother sealing head elements is not required. The selection andarrangement of heat pipe elements will depend upon the arrangement ofthe coil assembly and the required heat dissipation rate. Additionallythe condenser elements may be optionally attached to radiating elements,such as finned radiators, to further increase the heat transfer rate toair. In alternative embodiments, the evaporator elements may be directlyin contact with the ferrite core.

For the particular example shown in FIG.1 through FIG. 8, two heat pipesare used. Each heat pipe 40 consists of a single evaporator element 42that uses four connecting tubes 44 for connection to a plurality ofcondenser elements 46 via a common plenum 48. Each condenser element is“U” shaped with sufficient spacing between surfaces to allow maximumradiated heat transfer from the heat pipe's media to the surroundingambient air. Further, in this example, the planar face of each condenserelements 46 is oriented at an angle of substantially 90 degrees with theplanar surface (substantially parallel to coil plate 38, if used, andferrite core 32) of each evaporator element 42 and disposed relative tothe structure of the sealing head to give them optimum exposure to thesurrounding air for a maximum dissipation of heat load. Otherconfigurations of heat pipe 40, including quantity of heat pipes,quantity of evaporator and condenser elements, and connecting tubes, andorientation of the same can be used as appropriate for a particulardesign of the foil cap sealer of the present invention.

The foregoing embodiments do not limit the scope of the disclosedinvention. The scope of the disclosed invention is further set forth inthe appended claims.

What is claimed is:
 1. An induction foil cap sealing head comprising: acoil assembly comprising: a magnetic flux concentrator; and anair-cooled inductor disposed adjacent to the magnetic flux concentrator;a one or more heat pipes comprising: an at least one evaporator elementof the one or more heat pipes, the at least one evaporator element incontact with the magnetic flux concentrator; an at least one condenserelement of the one or more heat pipes; and a connector for connectingeach of the at least one evaporator element to each of the at least onecondenser element to provide passage of a heat transfer media throughthe one or more heat pipes; whereby the one or more heat pipes dissipateheat generated primarily in the magnetic flux concentrator andair-cooled inductor when a current in the air-cooled inductor produces amagnetic field that penetrates the magnetic flux concentrator.
 2. Theinduction foil cap sealing head of claim 1 wherein the coil assemblyfurther comprises a frame substantially surrounding the sides of themagnetic flux concentrator, and a cover plate disposed on the bottom ofthe air-cooled inductor.
 3. The induction foil cap sealing head of claim1 wherein the coil assembly further comprises a thermally conductivematerial disposed between the magnetic flux concentrator and the atleast one evaporator element.
 4. The induction foil cap sealing head ofclaim 1 wherein the air-cooled inductor comprises at least one Litzwire.
 5. The induction foil cap sealing head of claim 1 wherein themagnetic flux concentrator comprises a ferrite core of “U” shapedferrite segments and the air-cooled inductor is at least partiallyseated in the ferrite core.
 6. The induction foil cap sealing head ofclaim 1 wherein the connector is a tube.
 7. The induction foil capsealing head of claim 1 wherein a planar surface of the at least oneevaporator element lies in a plane that is substantially at 90 degreesrelative to a planar face of the at least one condenser element.
 8. Theinduction foil cap sealing head of claim 1 wherein the at least onecondenser element further comprises a plurality of “U” shaped condenserelements connected to a common plenum.
 9. An induction foil cap sealerfor sealing a foil cap to the opening of a container comprising: asealing head module comprising: a coil assembly comprising: a magneticflux concentrator; and an air-cooled inductor seated in the magneticflux concentrator; a one or more heat pipes comprising: an at least oneevaporator element of one or more heat pipes, the at least oneevaporator element in contact with the magnetic flux concentrator; an atleast one condenser element of the one or more heat pipes; and aconnector for connecting each of the at least one evaporator element toeach of the at least one condenser element to provide passage of a heattransfer media through the one or more heat pipes; and a power supplymodule comprising a power supply with an ac output, the power supplymodule remotely located from the sealing head module; and an at leastone electrical conductor connecting the ac output to the air-cooledinductor; whereby the one or more heat pipes dissipate heat generatedprimarily in the air-cooled inductor and magnetic flux concentrator whenthe ac output provides a current to the air-cooled inductor, whichproduces a magnetic field that penetrates the magnetic fluxconcentrator.
 10. The induction foil cap sealer of claim 9 furthercomprising a control panel mounted in the sealing head module, and an atleast one control cable connecting the control panel to the power supplymodule.
 11. The induction foil cap sealer of claim 9 wherein the coilassembly further comprises a frame substantially surrounding the sidesof the magnetic flux concentrator, and a cover plate disposed on thebottom of the air-cooled inductor.
 12. The induction foil cap sealer ofclaim 9 wherein the coil assembly further comprises a thermallyconductive material disposed between the magnetic flux concentrator andthe at least one evaporator element.
 13. The induction foil cap sealerof claim 9 wherein the air-cooled inductor comprises an at least oneLitz wire.
 14. The induction foil cap sealer of claim 9 wherein themagnetic flux concentrator comprises a ferrite core of “U” shapedferrite segments and the air-cooled inductor is at least partiallyseated in the ferrite core.
 15. The induction foil cap sealer of claim 9wherein the connector is a tube.
 16. The induction foil cap sealer ofclaim 9 wherein a planar surface of the at least one evaporator elementlies in a plane that is substantially at 90 degrees relative to a planarface of the at least one condenser element.
 17. An induction foil capsealing head comprising: a coil assembly comprising: a magnetic fluxconcentrator comprising a ferrite core of “U” shaped ferrite segments;and an air-cooled inductor at least partially seated in the magneticflux concentrator, the air-cooled inductor comprising an at least oneLitz wire; a one or more heat pipes comprising: an at least oneevaporator element of the one or more heat pipes, the at least oneevaporator element in contact with the magnetic flux concentrator; an atleast one condenser element of the one or more heat pipes; and aconnector for connecting each of the at least one evaporator element toeach of the at least one condenser element to provide passage of a heattransfer media through the one or more heat pipes; whereby the one ormore heat pipes dissipate heat generated primarily in the magnetic fluxconcentrator and air-cooled inductor when a current in the air-cooledinductor produces a magnetic field that penetrates the magnetic fluxconcentrator.
 18. The induction foil cap sealing head of claim 17wherein the coil assembly further comprises a thermally conductivematerial disposed between the magnetic flux concentrator and the atleast one evaporator element.
 19. The induction foil cap sealing head ofclaim 17 further comprising a thermal material for seating theair-cooled inductor against the magnetic flux concentrator.